1. Field of the Invention
This invention relates to hinges, and more specifically relates to hinges of plastic composition.
2. Description of the Prior Art
Door hinges are typically made of metallic materials because metals are strong and long lasting. Metal hinges, however, suffer from several limitations which have inspired inventors to attempt to construct better hinges. Chief among the limitations sought to be overcome is the corrosive aspect of metallic hinges. A metallic hinge performs poorly in the early stages of corrosion and becomes completely inoperable if the corrosion process is not stopped.
Moreover, metallic hings require frequent lubrication and in the absence of the required lubrication begin emitting aggravating noises.
Metallic hinges are also heavy and thus expensive to transport from the place of manufacture to the points of distribution. The consumer pays for the high cost of transportation of metal hinges, of course.
Finally, metallic hinges can generate sparks when struck and some environments must be carefully protected against sparks.
There is a need for a non-corrosive hinge that is strong yet light in weight. There is also a need for a hinge that does not require lubrication and which can be relied upon to not generate sparks when struck.
Attempts have been made by others to build hinges of plastic. Being non-metallic, plastic is not subject to corrosion and can not generate sparks when struck and is thus suitable for use where spark-producing materials are prohibited. Plastic is light in weight and plastic hinges can therefore be transported at reduced shipping costs vis a vis metallic hinges.
Despite the desireability of plastic as a material for hinges, however, earlier efforts to make hinges of plastic have failed. The only plastic hinge ever available to the public, as far as is known to the inventor of the device to be disclosed hereinafter, had to be withdrawn from the marketplace because it lacked the strength and durability to serve as a replacement for metal hinges. Specifically, a quantity of the same were installed on the doors of a motel chain (Holiday Inn) for test purposes. Many of the plastic hinges cracked as the screws were being tightened at the time of installation and the balance thereof cracked under normal use conditions a very brief period of time.
There is a clear need for a durable plastic hinge, but none appears in the prior art.